A friend’s grandfather grew tobacco in Kentucky before the war, and switched to hemp during the war, which was legal if you were growing it for rope for the military. Most of the US supply of rope came from the Philippines, which had already been occupied by the Japanese. If you grew something like 10 acres of it, you were exempt from the draft; too bad this was no longer the case during the Vietnam war 
After the war was over, they told him he had to switch back to tobacco. So he did, even though it’s a much nastier product to farm; it’s still a cash crop. At least in Kansas, the leftover ditchweed from hemp growing kept hippies in business harvesting the stuff during the 60s - it wasn’t very good, but you could get it, if you didn’t get caught.
